Meta-Analysis
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Oct 21, 2019; 25(39): 6025-6040
Published online Oct 21, 2019. doi: 10.3748/wjg.v25.i39.6025
Allicin as add-on therapy for Helicobacter pylori infection: A systematic review and meta-analysis
Xiao-Bei Si, Xu-Min Zhang, Shuai Wang, Yu Lan, Shuo Zhang, Lin-Yu Huo
Xiao-Bei Si, Xu-Min Zhang, Shuai Wang, Yu Lan, Department of Gastroenterology, Beijing Jishuitan Hospital, Beijing 100035, China
Shuo Zhang, Department of Cardiology, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences, Beijing 100037, China
Lin-Yu Huo, Department of Neurology, Beijing Haidian Hospital, Beijing 100080, China
Author contributions: Si XB, Lan Y, and Zhang S performed study design; Si XB and Zhang S performed study selection; Si XB and Wang S performed data collection; Si XB, Zhang XM, and Huo LY performed data analysis; Si XB performed manuscript drafting; Lan Y performed critical review of the manuscript. All authors revised the manuscript and approved the final version.
Supported by BeiJing JiShuiTan Hospital Foundation for Young Scholars, No. QN-201906.
Conflict-of-interest statement: There is no conflict of interest associated with any of the senior author or other co-authors who contributed their efforts in this manuscript.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Yu Lan, MA, Professor of Internal Medicine, Chief, Department of Gastroenterology, Beijing Jishuitan Hospital, No. 31, Xinjiekou East Street, Beijing 100035, China. lanyu@jsthospital.org
Telephone: +86-10-58398289
Received: August 1, 2019
Peer-review started: August 1, 2019
First decision: August 27, 2019
Revised: September 16, 2019
Accepted: September 27, 2019
Article in press: September 27, 2019
Published online: October 21, 2019
ARTICLE HIGHLIGHTS
Research background

Allicin (2-propene-1-sulfinothioic acid S-2-propenyl ester, diallyl thiosulfinate), a compound of garlic, was proved to be active in inhibiting Helicobacter pylori (H. pylori) growth in vitro. However, several clinical trials using garlic oil and fresh oral garlic failed to show improvements in H. pylori infection. In recent years, due to developments in pharmaceutical technology, commercial allicin tablets are available, with a series of randomized clinical trials that explored allicin as an add-on therapy to PPI therapy or bismuth containing quadruple therapy to treat H. pylori infection.

Research motivation

Allicin as an add-on therapy to treat H. pylori infection has been trialed, with variable results. Whether allicin could be medicated as an anti-H. pylori drug is still inconclusive.

Research objectives

We performed a meta-analysis to evaluate the efficacy and safety of allicin as an add-on therapy, i.e., allicin plus PPI triple therapy or bismuth containing quadruple therapy for H. pylori infection.

Research methods

Electronic databases including MEDLINE, EMBASE, Web of Science, etc. were searched. A meta-analysis was performed using the fixed-effects model for low heterogeneity and the random-effects model for high heterogeneity with sensitivity analysis. Bias was evaluated using Egger’s tests. Trial sequential analysis (TSA) was used to evaluate information size and treatment benefits. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the level of quality.

Research results

A total of eight RCTs consisting of 867 participants were included. As a result, add-on therapy of allicin combined with PPI triple therapy (PTT) or bismuth containing quadruple therapy (BCQT) showed a significantly higher eradication rate (93.33% vs 83.56%, P < 0.001) and healing rates of ulcer (86.17% vs 75.87%, P < 0.001). In addition, the total remission rate of peptic ulcers across all allicin groups was significantly higher than that of controls (95.99% vs 89.25%, P = 0.002). Such outcomes were graded as “low” (ulcer healing rates and total ulcer remission rates) or “very low” (eradication rates and side effects rates) according to the GRADE assessment.

Research conclusions

This study provides evidence that allicin improves eradication rates, healing rates, the remission of peptic ulcers, and the remission of abdominal pain, but does not affect side effects when used as an add-on treatment for H. pylori infection and H. pylori related ulcers. In other words, allicin plus PPI triple therapy or bismuth containing quadruple therapy may obtain better therapeutic effects.

Research perspectives

The present review evaluated the efficacy and safety of allicin as an add-on therapy for H. pylori infection, with conclusion that allicin might improve healing rate and symptom remission of H. pylori related ulcers as well as H. pylori eradication rate. However, there are still many questions remaining unclear. On one hand, the exact mechanism of allicin as an anti-H. pylori drug is not clear up till now. On the other hand, further clinical evidence of high quality is still needed since the present evidence is of “low” or “very low” quality.